“I’m so sorry to let you guys down and I promise I will make it up as soon as I can,” Cabello tweeted. “I guess sometimes I just push myself too hard and I promise I’m gonna take better care of myself.

Cabello and Charli XCX are the warm-up acts on Swift’s reputation tour, which kicked off May 8. The only Canadian stop is in Toronto on Aug. 3 and 4.